Well, if they are lies it would be "Bearing False Witness"... However, the whole premise of the religion is that folks are not perfect, only one person was and he was also God. So, by that god's grace they'd be forgiven if it were a sin. Denying that grace is a bit non-Christian though...
There's also that uncomfortable bit about judging others only to be judged by your own rules... If we take that all the way out, almost no human will be judged by all that forgiveness as almost every human I have seen runs around telling folks that God would "never forgive" them for something. If such is the case, and because you judged others using that premise, you would be judged that way too...
Nobody will be going to Heaven, because everyone seems to ignore Grace...